Cotype material is deposited in the mineralogical collections of Queens's University (Miller collection), Ontario, Canada, catalogue number M8224 (holotype) and M7138 (cotype), and the Natural History Museum London, specimen number BM2016,101 (cotype)

ADDENDUM

Potassicmendeleevite-(Ce) (not a valid species)

Although erroneously marked as “A” (= Approved) in the IMA List of Minerals for some years, only recently we became aware that actually the mineral has not yet been approved (only the name was approved). Accordingly potassicmendeleevite-(Ce) has been omitted from the list of valid species.

REVISED CHEMICAL FORMULA

A paper on the mineral nickelskutterudite has been published recently [American Mineralogist, 102, 205-209 (2017)] in which the ideal chemical formula of the mineral is given as (Ni,Co,Fe)As3. In this formula, based on new EPMA and SCXRD data, and on crystal-chemical arguments, both Co and Fe must be present as subordinate yet essential components, and no As deficiencies were observed (the previously accepted formula of nickelskutterudite was NiAs3–x). These data were examined carefully by the CNMNC officers and were considered reliable. Accordingly it was agreed to modify the formula of nickelskutterudite in the official IMA List of Minerals. Similarly, the formula of skutterudite becomes now CoAs3 (it was CoAs3–x).